I've figured out to install the module by login into ssh and type (centos 6.7 64 bits)
pecl install stats
installation went ok.
in fact it showed the following:
"Build process completed successfully
Installing '/usr/local/lib/php/extensions/no-debug-non-zts-20131226/stats.so'
install ok: channel://pecl.php.net/stats-1.0.5
configuration option "php_ini" is not set to php.ini location
You should add "extension=stats.so" to php.ini"
I've added at the end of php.ini (in Centoswebpanel at the php.ini configuration) this: extensions=stats.so
then restarted httpd service and Voila!
hope this helps to others!